Fourier transform mass spectrometry (FTMS) is a rapidly developing new instrument concept with possible important application to biomolecule research, especially large non-volatile molecule. The objectives of this program are to develop a Cs+ desorption ionization source adaptable to FTMS and pursue the development of high mass FTMS with specific emphasis on biomolecules. In this proposal the unique aspects of FTMS for biomolecule studies, i.e., high sensitivity/high resolution, are discussed and specific examples of preliminary studies are presented. The continued development of biomolecule FTMS is presented with particular emphasis on high mass molecules (greater than m/z 1,000) using Cs+ desorption ionization. The model systems proposed for extensive study include vitamins (vitamin B12 and vitamin B12 coenzyme), antibiotics (avoparcin and adenomycen, etc.), peptides (melittin and glucagon), and bovine insulin. These molecules span the mass range m/z 1,000 - m/z 5,000 and the present available mass range of FTMS. Also, these molecules represent suitable challenges to provide a critical accessment of FTMS for the analysis of biomolecules.